The 2 1/2" Wilkins 450 is a double check valve assembly began production in 1998 and is still currently being produced. The body is constructed of epoxy coated ductile iron and is an "N" pattern device. Configuration can be adjusted for vertical mounting or N" shape. Check assemblies are a plastic cam check design and springs are self contained. Spring tension does not need to be released to replace rubber discs. Retainer clips hold the checks in place. The 450 uses a single victaulic clamp style cover. In 2010, all bronze parts (test cocks, bulkhead fittings, ect.) were transitioned to lead free bronze to adhere to new codes. No special tools are required for servicing.